1. Field of Invention
The invention relates to an apparatus for deterring an animal from barking including a vibration sensor. More specifically, the invention relates to an apparatus for deterring an animal from barking with an internal vibration sensor.
2. Description of the Related Art
Nuisance barking is common problem for dog owners. One common solution is to use a bark deterrent apparatus that discourages the dog from barking. A conventional bark deterrent apparatus detects a dog's bark using an audio sensor, a mechanical vibration sensor, or a combination of these technologies. For clarification, as used herein, the term “vibration” refers to mechanical vibrations communicated by physical contact and the term “audio” refers to sound waves carried by air at frequencies within the range of human hearing. Both audio sensors and mechanical vibration sensors can be used for detecting barks and each has its own advantages and disadvantages. Mechanical vibration sensors are useful because they consume significantly less power than a microphone. However, conventional designs using a mechanical vibration sensor involve the use of an external probe to couple the vibrations in the dog's throat to the piezoelectric element.
The use of an external probe is an industry standard with proven effectiveness. In the prior art, the piezoelectric element is considered part of the electronics generally protected by locating it within the housing on a circuit board. Commercially effective bark deterrent devices continue to use an external, protruding vibration probe continues in mechanical vibration sensors despite the limitations and perceptions associated with them based on a need to maintain a physical connection between the piezoelectric element and the dog's throat to effectively detect barks. Considerable effort has been spent by those in the art to develop the prior art bark sensors with external, protruding vibration probes that are currently used for bark detection.
It is instructive to understand the relationship of prior art bark sensors, protruding vibration probes, and electrodes to bark detection. First, electrodes are either rigid in design and exhibit virtually no movement when secured to the housing, effectively serving as extensions of the housing with respect to mechanical vibrations, or are compliant in design to relieve pressure, effectively serving to dampen vibrations. Prior art external, protruding vibration probes were designed to allow movement in response to mechanical vibrations. The prior art vibration probes include a rigid post in communication with a piezoelectric element and passing through an opening in the housing, a plastic probe cover screwed on to the exposed end of the rigid post and making physical contact with the dog's throat, an external O-ring to provide the primary waterproof seal while allowing the rigid post to move in response to vibrations from the dog's throat, and an internal O-ring to provide a secondary waterproof seal while allowing the rigid post to move in response to vibrations from the dog's throat. This design retains a risk of failure of the weatherproof seal potentially leading to damage of the internal circuitry. The O-rings also serve to isolate the vibration probe from the housing so mechanical vibrations introduced into the housing are not detected as bark signals. U.S. Pat. No. 6,668,760, issued to Groh, et al., on Dec. 30, 2003 describes the general construction of a prior art external, protruding vibration probe designed to have the vibration probe communicate only vibrations originating at the dog's throat and to avoid registering other events such as a branch striking the housing. This design allows the vibration probe to move independently of the housing.
In combination with the piezoelectric element and an optional amplifier, a vibration probe forms a prior art vibration sensor. To further eliminate unwanted vibrations, the prior art includes efforts to mechanically isolate the piezoelectric element from vibrations propagated through the housing, which is also described in U.S. Pat. No. 6,668,760. With the vibration probe isolated from the housing and the piezoelectric element isolated from the housing, any vibrations detected can be considered to have originated from the dog.
U.S. Pat. No. 5,927,233, issued to Christopher E. Mainini on Jul. 27, 1999 discloses prior art bark deterrent apparatus that delivers an electrical shock stimulus. The bark deterrent apparatus includes a housing attached to a collar worn about the dog's neck. There are three probes extending from the housing: two probes associated with delivering the electrical shock stimulus and one for communicating vibrations from the dog's throat to the internal piezoelectric element. The vibration sensor probe competes with the two adjacent electrode probes for contact pressure, sometimes requiring the collar tension to be increased. Understandably, the pet owner may be reluctant to properly tighten the collar because of the perceived discomfort caused by the probes even when the dog is not engaging in nuisance barking. A collar fitted too loosely results in an ineffective deterrent because the probes are not properly engaging the dog to deliver the electrical stimulus or pick up the vibrations at the dog's throat.
The addition of a vibration detection probe positioned between the two electrodes further complicates the process of ensuring a proper fit. Unless properly fitted, the vibration probe and one of the electrodes may adequately engage the dog's neck while the other electrode makes little or no contact and prevent an effective stimulus from being delivered. Even when fitted properly, the distribution of contact pressure between the vibration and the electrodes can result in reduced effectiveness of the stimulus. Also, a loosely fitted bark deterrent apparatus is susceptible to moving from the optimal training position centered on the dog's neck with the electrodes at the throat area. The central vibration probe unbalances the pair of electrodes and provides a pivot point that contributes to the movement from the optimal position.
U.S. Pat. No. 5,601,054, issued to Ho-Yun So on Feb. 11, 1997 combines the functions of delivering the electrical shock stimulus and the communication of vibrations into a single probe, which would eliminate the unbalancing caused by the central vibration probe. Alternately, U.S. Pat. No. 7,252,051, issued to Francisco J. Napolez, et al., on Aug. 7, 2007 adds an offset stabilizing post to balance the bark control device.
The perception and fitment issues may even be greater for pet owners who choose to use deterrents other than an electrical shock stimulus for various reasons. U.S. Pat. No. 6,668,760 also represents a prior art bark deterrent apparatus using a spray deterrent. Unlike an electrical shock stimulus, application of the spray deterrent does not require electrodes. Accordingly, the only probe on the bark deterrent apparatus is the vibration probe. Even when only one external probe exists, the perception of discomfort remains. Further, having only one probe extending from the housing creates a pivot point on which the bark deterrent apparatus may rock in any direction.
In addition to construction, fitment, and perception issues, there is a quality issue. The bark waveforms obtained using prior art vibration probes are of lower quality than can be obtained using higher quality audio transducers such as condenser, capacitor, or electrostatic microphones. However, the higher quality audio transducers require significant power and tend to quickly deplete limited power supplies, such as batteries. In contrast, vibration transducers have low power consumption. Accordingly, vibration sensors have found use as triggering devices to wake up the microcontroller and the audio transducer for accurate bark detection. This arrangement improves battery life while retaining the ability to perform high quality bark detection. This technique is described in detail in U.S. Pat. No. 5,927,233. Audio transducers are also prone to picking up ambient sounds, including barks by another dog, which can result in false triggering. Because the vibration transducer responds primarily to contact vibrations, it is generally non-responsive to sound-induced vibrations excepting those produced at close range and loud volumes. The result is that the vibration sensor effectively responds only to events directly associated with the dog wearing the bark deterrent apparatus. Despite the higher quality bark signals obtainable from audio transducers, prior art vibration sensors have found use for bark detection in some entry-level training devices primarily based on the low power consumption, cost, and the ability to localize the source of the bark to dog wearing the collar.
Bark detection accomplished solely using vibration sensors is more susceptible to false triggers as a result of the lower quality bark signals obtained and the greater likelihood of vibrations transferred through the housing being interpreted as a bark, even when using O-rings to isolate the vibration probe. Often the level of false triggers rises to unacceptable levels because the undeserved corrections hamper effective training. To reduce the number of false triggers, U.S. Pat. No. 7,222,589, issued to Albert L. Lee, IV, et al., on May 29, 2007 discloses the application of vibration dampening coatings to the exterior of the housing in order to minimize the propagation of vibrations through the housing.
Finally, two variations of the external, protruding probe have been used. The first is the collar-mounted vibration transducer disclosed in U.S. Pat. No. 4,947,795, issued to Gregory J. Farkas on Aug. 14, 1990 in which the vibration transducer is held against the dog's neck by the collar. Few details about the vibration transducer are provided, but the disclosure suggests that the vibration transducer itself is placed in contact with the dog's throat to measure vibrations. The second is described in U.S. Pat. No. 7,252,051, issued to Francisco J. Napolez, et al., on Aug. 7, 2007 in which the vibration transducer is contacted by a covered probe referred to as a nipple formed on the underside of the dome-shaped membrane. Although effectively hidden by a membrane, the membrane-covered probe moves and transfers vibrations to the vibration transducer independently of the housing.